High voltage isolation devices for semiconductor devices

ABSTRACT

High voltage isolation devices for semiconductor devices and associated systems, are disclosed herein. The isolation device may support operations of a 3-dimensional NAND memory array of the semiconductor device. In some embodiments, during high voltage operations (e.g., erase operations), the isolation device may provide a high voltage to the memory array while isolating other circuitry supporting low voltage operations of the memory array from the high voltage. The isolation device may include a set of narrow active areas separating the low voltage circuitry from the high voltage and a gate over the narrow active areas. In a further embodiment, the isolation device includes interdigitated narrow active areas and a common gate over the interdigitated narrow active areas to reduce an area occupied by the isolation devices.

TECHNICAL FIELD

The present technology generally relates to semiconductor devices, andmore particularly relates to high voltage isolation devices forsemiconductor devices.

BACKGROUND

Semiconductor devices are widely used to store information related tovarious electronic devices such as computers, wireless communicationdevices, cameras, digital displays, and the like. Information is storedby programming different states of a memory cell. Various types ofsemiconductor memory devices exist, such as non-volatile memory devices(e.g., NOR flash memory devices, 3-dimensional NAND flash memorydevices, etc.) and volatile memory devices (e.g., dynamic RAM (DRAM),synchronous dynamic RAM (SDRAM), etc.).

Improving memory devices, generally, may include increasing memory celldensity, increasing read/write speeds or otherwise reducing operationallatency, increasing reliability, increasing data retention, reducingpower consumption, reducing areas occupied by integrated circuitry, orreducing manufacturing costs, among other metrics. One way of reducingmanufacturing costs is to improve manufacturing processes to increasethe margin of successfully manufactured devices. Manufacturers canimprove the manufacturing margin by implementing processes that, forexample, increase the consistency or tolerance of manufacturing steps(e.g., removal or deposition of materials), improve the scale ofmanufacturing, reduce variability among memory cells, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present technology can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present technology.

FIGS. 1A-1C are layouts of isolation devices in accordance withembodiments of the present technology.

FIGS. 2A-2C are layout options for isolation devices in accordance withembodiments of the present technology.

FIG. 3 is a schematic view of a system that includes a memory deviceincluding isolation devices in accordance with embodiments of thepresent technology.

DETAILED DESCRIPTION

Embodiments of the present technology include isolation devices forsemiconductor devices—e.g., 3-dimensional (3D) NAND memory devices. Theisolation devices, during certain operations of the memory devices(e.g., erase operations), may couple relatively high voltages (HVs) tomemory cells of the memory devices while isolating other components(e.g., page buffers) of the memory devices from the high voltages.During other operations of the memory devices (e.g., read/writeoperations), the isolation devices may couple the memory cells to othercomponents (e.g., page buffers) of the memory devices, which operatewith relatively low voltages (LVs). Accordingly, such isolation devicesmay be referred to as LV-HV isolation devices or high voltage isolationdevices.

In some embodiments, the isolation devices include narrow active areasconfigured to couple (or decouple) subsets of the memory cells to (orfrom) corresponding page buffers. To this end, the isolation devicesinclude gates coupled with the narrow active areas to controlconductivities of the narrow active areas through a gate dielectricmaterial. Further, the isolation devices may be placed next to eachother (e.g., side by side) such that a first group of narrow activeareas of a first isolation device may be located adjacent to a secondgroup of narrow active areas of a second isolation device. Accordingly,a first gate of the first isolation device disposed over the first groupof narrow active areas can be located next to a second gate of thesecond isolation device disposed over the second group of narrow activeareas.

As described in more detail herein, a length of the isolation device maybe determined by configurations of memory arrays of the memory devices.For example, a quantity of the narrow active areas along the length ofthe isolation device corresponds to a quantity of bit lines of thememory array that the isolation device supports. A width of theisolation device, however, may be scaled independently of the memoryarray configuration such that an area occupied by the isolation devicescan be reduced. For example, the first and second groups of narrowactive areas may be interdigitated such that individual narrow activeareas of the first group alternate with individual narrow active areasof the second group. Further, the first and second gates may be combinedinto one common gate over the interdigitated active areas such that thecommon gate can be shared by the first and second groups of the narrowactive areas. The sharing of the common gate is feasible because thefirst and second gates are concurrently biased to a same voltage duringthe isolation device operations.

Additionally, or alternatively, widths of the first and second narrowactive areas may be reduced (e.g., to a minimum feature size of thememory devices) to facilitate interdigitating the first and secondnarrow active areas. Further, widths of the first and second gates overthe first and second narrow active areas may be reduced such that thefirst and second isolation devices can be brought closer to each other.In this manner, the area occupied by the isolation devices may bereduced to support ever-increasing quantity of memory cells built in aunit area of the memory devices and/or to reduce areas (e.g.,footprints) occupied by the isolation devices.

Numerous specific details are disclosed herein to provide a thorough andenabling description of embodiments of the present technology. Moreover,the present technology may have additional embodiments, and may bepracticed without several of the details of the embodiments describedbelow with reference to FIGS. 1A through 2C. For example, some detailsof semiconductor devices well known in the art have been omitted so asnot to obscure the present technology. In general, it should beunderstood that various other devices and systems in addition to thosespecific embodiments disclosed herein may be within the scope of thepresent technology.

As used herein, the terms “vertical,” “lateral,” “upper,” “lower,”“above,” and “below” can refer to relative directions or positions offeatures in the semiconductor devices in view of the orientation shownin the Figures. For example, “upper” or “uppermost” can refer to afeature positioned closer to the top of a page than another feature.These terms, however, should be construed broadly to includesemiconductor devices having other orientations, such as inverted orinclined orientations where top/bottom, over/under, above/below,up/down, and left/right can be interchanged depending on theorientation.

A person skilled in the relevant art will recognize that suitable stagesof the methods described herein can be performed at the wafer level orat the die level. Therefore, depending upon the context in which it isused, the term “substrate” can refer to a wafer-level substrate or to asingulated, die-level substrate. Furthermore, unless the contextindicates otherwise, structures disclosed herein can be formed usingconventional semiconductor-manufacturing techniques. Materials can bedeposited, for example, using chemical vapor deposition, physical vapordeposition, atomic layer deposition, spin coating, and/or other suitabletechniques. Similarly, materials can be removed, for example, usingplasma etching, wet etching, chemical-mechanical planarization, or othersuitable techniques. A person skilled in the relevant art will alsounderstand that the technology may have additional embodiments, and thatthe technology may be practiced without several of the details of theembodiments described below with reference to FIGS. 1A through 2C.

FIG. 1A describes various features of the high voltage isolation devicein accordance with embodiments of the present technology. Moreover,operating principles of the isolation device are described withreference to FIG. 1A. FIGS. 1B and 1C illustrate aspects of theisolation device included in a semiconductor device to supportoperations of a memory array of the semiconductor device. FIGS. 2Athrough 2C illustrate layout options of the isolation device havinginterdigitated narrow active channels and a common gate over the activechannels to reduce footprints of the isolation devices. The layoutoptions illustrate various modifications directed to the interdigitatednarrow active channels and the common gate. Further, trade-offs betweenthe footprints of the isolation devices and risks associated withleakage currents during high voltage operations are described withreference to FIGS. 2A through 2C.

FIG. 1A is a layout of a portion of an isolation device 110 inaccordance with embodiments of the present technology. In someembodiments, the isolation device 110 is part of a memory device (e.g.,a 3D NAND memory device). Further, the isolation device 110 may belocated under a memory array (e.g., an array of 3D NAND memory cells) tosupport operations of the memory device directed to the memoryarray—e.g., erase operations, read/write operations. The isolationdevice 110 includes active areas (e.g., an active area 115, active areas120 (also identified individually as 120 a-f)), gates (e.g., first gates125 (also identified individually as 125 a/b), second gates 130 (alsoidentified individually as 130 a/b), and contacts to the active areasand to the gates. The contacts to the active areas includes sourcecontacts 135, bit line contacts 140 (also identified individually as 140a/b), and contacts 145 (also identified individually as 145 a/b) at endportions of the active areas 120. The contacts to the gates includescontacts 150 (also identified individually as 150 a/b) to the firstgates 125 and contacts 155 (also identified individually as 155 a/b) tothe second gates 130. Additionally, the isolation device 110 includesother features (e.g., interconnects in dielectric layers, not shown) andmay be coupled with other integrated circuitry and/or components of thememory device—e.g., a control circuit driving the isolation device 110,a memory array, page buffers, etc.

Active areas 115 and 120 correspond to areas of a substrate (e.g., asilicon substrate, in which the memory devices are fabricated)surrounded by dielectric materials providing electrical isolations amongactive areas of the substrate—e.g., dielectric materials in shallowtrench isolation (STI) features in the substrate, which may be referredto as field regions. Further, the active areas 115 and 120 may includeone or more dopant species that modify electrical and/or materialcharacteristics of the active areas. As such, the active areas 115 and120 may be referred to as diffusion areas and/or diffusion regions. Forexample, the active areas 115 and/or 120 may form source, channel,drain, and/or lightly-doped drain (LDD) regions of field-effecttransistors (FETs) by selectively introducing one or more dopant speciesin various portions of the active areas. Further, active areas of thesubstrate may include other components of the memory device, such asdiffusion resistors, wells, ground nodes, or the like.

The first and second gates 125 and 130 may include poly-crystallinesilicon (poly-Si), metallic elements (e.g., tungsten (W), titanium (Ti),tantalum (Ta), etc.), silicides including the metallic elements (e.g.,WSix), or a combination thereof. During operations of the isolationdevice 110, the first and second gates 125 and 130 may capacitivelycouple with the active areas underneath (e.g., channels of FETs) througha dielectric material to control (e.g., determine, modify)conductivities of the active areas. The dielectric material locatedbetween the active area and the first and second gates 125 and 130 maybe referred to as gate dielectrics. The gate dielectrics may includesilicon oxide, silicon nitride, oxides including high-k elements (e.g.,hafnium (Hf), zirconium (Zr), lanthanum (La), etc.), silicates includingthe high-k elements (e.g., Hf-silicates, Zr-silicates), or a combinationthereof.

The contacts 135 through 155 include conductive materials to couplevarious nodes of the isolation device 110 to other functional featuresor operational voltages of the memory device—e.g., a control circuitthat operates the isolation device 110, a memory array, page buffers,etc. The contacts 135 through 155 may be filled with tungsten (W), andmay be referred to as W0 contacts. The W0 contacts (and/or metallictraces connected thereto) may correspond to the lowest contacts and/orinterconnects (e.g., formed earlier than other conductive features inthe process flow fabricating interconnects of the memory device) thatcan be formed on the active areas 115 and 120, and the first and secondgates 125 and 130.

In some embodiments, the active area 115 may be regarded to include amedial region 116 (e.g., central region) where a column of sourcecontacts 135 are located. Further, the active area 115 includes outerregions 117 (also identified individually as 117 a/b) (e.g., regionsperipheral to the central region) where columns of bit line contacts 140are located, respectively. Each individual bit line contacts 140 can becoupled to a corresponding bit line of the memory array.

The isolation device 110 also includes first gates 125 disposed over theactive area 115. Individual first gates 125 may be regarded to havestraight portions 126 (also identified individually as 126 a/b) betweenthe column of source contacts 135 and the columns of bit line contacts140 a/b, respectively. As such, the straight portions 126 of the firstgates 125 may couple (or decouple) the source contacts 135 to (or from)the bit line contacts 140 based on a voltage applied to the first gates125 through the contacts 150. Further, individual first gates 125include sets of protruded segments 127 (also identified individually as127 a/b) that extend past the edges 118 (also identified individually as118 a/b) of the outer regions 117 in a first direction orthogonal to thecolumn of bit line contacts 140. Individual protruded segments 127 ofthe first gates 125 are located between two neighboring bit linecontacts 140 such that the protruded segments 127 can assist isolatingthe neighboring bit line contacts 140 from each other.

Further, the isolation device 110 includes a set of active channels 120(e.g., narrow, elongated active areas that forms channels) connected tothe edge 118 of the outer region 117. In this regard, a singlecontiguous active area may include both the active region 115 and theset of active channels 120. Each one of the active channels 120 isaligned with a corresponding bit line contact 140. Moreover, eachindividual active channel extends in the first direction (e.g.,orthogonal to the column of bit line contacts 140) and includes an endportion away from the edge 118, where a contact 145 is located.Individual contacts 145 may be coupled to corresponding page buffers ofthe memory device. In this manner, page buffers can be coupled to (ordecoupled from) corresponding bit line contacts 140 through individualcontacts 145 (i.e., individual end portion of the active channelsincluding the contact 145) during the operations of the memory array.

The isolation device 110 also includes a second gate 130 over the set ofactive channels 120, where the second gate 130 extends in a seconddirection orthogonal to the first direction—e.g., parallel to the columnof bit line contacts 140. Moreover, the second gate 130 is locatedbetween the column of bit line contacts 140 and the contacts 145. Assuch, the second gate 130 may couple (or decouple) the bit line contacts140 to (or from) the contacts 145 (thus, the page buffers coupled to thecontacts 145) based on a voltage applied to the second gate 130 throughthe contacts 155.

During a first operation of the memory device under a relatively lowvoltage (LV)—e.g., LV operations, read/write operations, the first gate125 may be turned off (e.g., grounded, deactivated) to decouple thesource contacts 135 from the bit line contacts 140. Further, the secondgate 130 may be turned on (e.g., activated) to couple the bit linecontacts 140 to the contacts 145. In this manner, individual bit linesof the memory array coupled to the bit line contacts 140 can be coupledto corresponding page buffers either to read data from the memory cellsof the bit lines to the page buffers or the write data from the pagebuffers to the memory cells of the bit lines. In some embodiments, thelow voltage may vary between approximately 0.5V (e.g., 0.5V±5%,0.5V±10%, or the like) to approximately 2.4V (e.g., 2.4V±5%, 2.4V±10%,or the like) to support various operations specified in the datasheetsof the memory device. Under certain operating conditions (e.g., testoperations), the low voltage may reach approximately 3.6V (e.g.,3.6V±5%, 3.6V±10%, or the like).

During a second operation of the memory device under a relatively highvoltage (HV)—e.g., HV operations, erase operations, the high voltage(e.g., an erase voltage of approximately 15V to approximately 25V) maybe applied to the source contacts 135. The first gate 125 may be turnedon to couple the source voltage (i.e., the voltage of the medial region116 where the source contacts 135 are located) to the bit line contacts140 such that the erase voltage may be passed on to the memory array.Further, the second gate 130 may be turned off (e.g., grounded,deactivated) to decouple the bit line contacts 140 from the contacts 145to isolate the high voltage from the contacts 145 (thus, from the pagebuffers coupled thereto). In some embodiments, the high voltage may varybetween approximately 10V (e.g., 10V±5%, 10V±10%, or the like) toapproximately 35V (e.g., 35V±5%, 35V±10%, or the like). As such, in someembodiments, a thickness of a gate dielectric material for the secondgate 130 may be thick enough to sustain the high voltage across the gatedielectric material—e.g., the thickness ranging from approximately 35nanometers (nm) to approximately 45 nm. In this manner, individual bitlines of the memory array can be coupled to the erase voltage while thepage buffers are isolated from the erase voltage.

FIG. 1B is a layout of the isolation device 110 in accordance withembodiments of the present technology. The isolation device 110 isdepicted to have a width W and a length L. Further, certainarchitectural aspects of the memory array may determine physicaldimensions of the isolation device 110—e.g., the length L set by alength of a memory plane. For example, the length L of the isolationdevice 110 may be determined based on a quantity of bit lines of thememory array that the isolation device 110 supports. In this regard, aquantity of the narrow active areas 120 along the length of theisolation device 110 may correspond to a quantity of bit lines of thememory array. In some embodiments, the length L may vary betweenapproximately 1,000 micrometers (μm) to approximately 10,000 μm. Thewidth W of the isolation device 110, however, may be relativelyindependent of the memory array architecture. In some embodiments, thewidth W may vary between approximately 5 μm to approximately 8 μm. Assuch, the width W may be reduced as described in more detail withreference to FIGS. 1C and 2A-2C.

FIG. 1C is a layout illustrating a pair of isolation devices 110 (alsoidentified individually as isolation devices 110 a and 110 b) inaccordance with embodiments of the present technology. The isolationdevices 110 a and 110 b are positioned side-by-side such that the activechannels 120 a and 120 b are next to each other. Further, the isolationdevices 110 a and 110 b may operate in pairs. For example, the secondgates 130 a and 130 b may be biased together during operations of theisolation devices 110 a and 110 b. As such, the second gates 130 a and130 b may be combined into one common gate as described with referenceto FIGS. 2A-2C. Further, the active channels 120 a and 120 b may beinterdigitated such that individual active channels 120 a alternate withindividual active channels 120 b. In this manner, the isolation devices110 a and 110 b can be brought closer to each other such that a totalwidth corresponding to both isolation devices 110 a and 110 b (e.g.,having the interdigitated active channels and the common gate shared bythe interdigitated active channels) can be less than a sum of the widthsof two individual isolation devices 110 a and 110 b (e.g., 2W).

In some embodiments, the thickness of the gate dielectric material forthe second gates 130 can be reduced if, during the HV operations (e.g.,erase operations), the high voltage (e.g., the erase voltage) coupled tothe bit line contacts 140 is substantially distributed across LDDregions 160 of the active channels 120. In other words, while the secondgate 130 is deactivated (e.g., grounded) during the HV operations, theelectric field across the gate dielectric material may be reduced due tothe voltage drop across the LDD regions such that the thickness of thegate dielectric material can be reduced. For example, the thickness ofthe gate dielectric material for the second gates 130 can be reduced toa thickness devised to support the relatively low voltage operations ofthe semiconductor device—e.g., the thickness ranging from approximately3.5 nm to approximately 7.5 nm, which correspond to 1.8V to 3.3Voperations, respectively. The LDD region 160 refers to part of theactive channels 120 between the bit line contact 140 (or the edge 118 ofthe outer region 117) and an edge of the second gate 130 facing the bitline contact 140.

In this regard, the widths (denoted as Wch in FIG. 1C, which may varybetween approximately 110 nm to approximately 150 nm in someembodiments) of the active channels 120 may be reduced (e.g., to aminimum feature size of the memory device) to increase resistance of theLDD region facilitating the voltage drop across the LDD region. Forexample, the widths of the active channels 120 may be reduced toapproximately 100 nm (or less) corresponding to a minimum feature sizefor the active layer. Further, the reduced gate oxide thicknessfacilitates reducing the gate lengths (denoted as Lg in FIG. 1C, whichmay vary between approximately 200 nm to approximately 500 nm in someembodiments) of the second gate 130—e.g., without experiencing shortchannel effects. Moreover, the active channels 120 b can be offset(e.g., shifted upward or downward) with respect to the active channel120 a such that the active channels 120 a and 120 b can be broughttogether to form interdigitated active channels. For example, the activechannels 120 b can be offset by one-half of the pitch (denoted as P inFIG. 1C, which may vary between approximately 400 nm to approximately650 nm in some embodiments) of the active channels 120 a and 120 b.Additionally, a common gate (e.g., a combination of the second gates 130a and 130 b) can be disposed above the interdigitated active channelssuch that the active channels 120 a and 120 b can share the common gateas described with reference to FIGS. 2A-2C.

FIG. 2A illustrates layouts 201 and 202 of a portion of an isolationdevice 210 in accordance with embodiments of the present technology. Theisolation device 210 may be an example of or include aspects of theisolation device 110 described with reference to FIGS. 1A-1C. Thelayouts 201 and 202 may be regarded as the region 170 of the isolationdevices 110 a and 110 b illustrated in FIG. 1C, which has been modifiedto form interdigitated active channels and a common gate shared by theinterdigitated active channels such that an area occupied by theisolation devices 110 a and 110 b can be reduced. The layout 201illustrates active, gate, and contact layers to describe variousfeatures of the isolation device 210 with the interdigitated activechannels and the common gate. The layout 202 illustrates implant layersoverlaid to the active, gate, and contact layers of the layout 201 toillustrate additional features of the isolation device 210.

The layout 201 illustrates active areas 215 (also identifiedindividually as 215 a/b) that include aspects of the active areas 115,such as medial regions (not shown), outer regions 217 (also identifiedindividually as 217 a/b), and edges 218 (also identified individually as218 a/b) of the outer regions 217. The medial regions of the activeareas 215 includes one or more source contacts (e.g., the sourcecontacts 135, not shown in the layout 201), and the outer regions 217includes bit line contacts 140 (also identified individually as 140a-e). The bit line contacts 140 may be viewed to form columns of bitline contacts in the outer regions 217.

The layout 201 also illustrates a set of interdigitated active channelsincluding a set of first active channels 220 a (one of which isidentified as 220 a 1) and a set of second active channels 220 b (one ofwhich is identified as 220 b 1). The sets of first and second activechannels 220 a/b are connected to edges 218 of the outer regions 217,respectively. Each one of the first and second active channels 220 a/bis aligned with a corresponding bit line contact 140 and extends in afirst direction orthogonal to the columns of bit line contacts 140. Asshown in the layout 201, individual first active channels 220 aalternate with individual second active channels 220 b to form the setof interdigitated active channels between the outer regions 217 a/b. Inthis regard, the set of second active channels 220 b may have beenoffset by a distance (e.g., shifted up or down by the distance in adirection orthogonal to the active channels 220) with respect to the setof first active channels 220 a, or vice versa. In some embodiments, thedistance corresponds to one-half of a pitch (denoted as P in FIG. 2A,which may vary between approximately 400 nm to approximately 650 nm insome embodiments) of the first active channels 220 a (or the secondactive channels 220 b).

Further, the first and second active channels 220 a/b may have a width(denoted as Wch in FIG. 2A, which may vary between approximately 110 nmto approximately 150 nm in some embodiments) orthogonal to the firstdirection. In some embodiments, the width corresponds to a minimumfeature size of the semiconductor device, which may be based on aprocess technology node to fabricate the semiconductor device. Forexample, the width may be approximately 100 nm (or less). As describedabove, the active channels 220 with the minimum width may facilitatedistributing a high voltage (e.g., the erase voltage) coupled to the bitline contacts 140 across the LDD region of the active channels 220 suchthat a thickness of the gate dielectric material above the activechannels 220 a/b can be reduced—e.g., to a thickness supportingrelatively low voltage operations of the semiconductor device.

The first and second active channels 220 a/b includes end portions 221a/b where contacts 145 a/b are located. The contacts 145 a/b may becoupled to page buffers of the memory device. The end portions 221 a/bare away from corresponding edges 218 a/b of the outer regions 217 a/b,and may have different (e.g., greater) dimensions than the width (Wch)of the active channels. For example, the end portions 221 a/b includesactive area endcaps surrounding the contacts 145 a/b such that thecontacts 145 a/b are within the endcaps of the end portions 221 a/bindependent of statistical process variations (e.g., variations incritical dimensions (CDs) of the contacts 145 a/b and/or the endportions 221 a/b, fluctuations in registrations between the active layerand the contact layer).

The layout 201 illustrates a common gate 280 over the set ofinterdigitated active channels. The common gate 280 extends in a seconddirection parallel to the columns of bit line contacts 140 and coupleswith the set of interdigitated active channels through the gatedielectric material disposed between the common gate 280 and theinterdigitated active channels. That is, the common gate 280 is sharedby the first and second active channels 220 a/b—e.g., two separate gates130 a/b depicted in FIG. 1C are combined into the common gate 280. Thecommon gate 280 is located between two end portions 221 a and 221 b ofthe opposing active channels 220 a and 220 b, within which the contacts145 a/b are located.

Further, the common gate 280 includes a straight portion 281 having awidth (denoted as Lw in FIG. 2A, which may vary between approximately 60nm to approximately 200 nm in some embodiments), a set of first segments282 a extending from a first edge of the straight portion 281 by adistance (denoted as D in FIG. 2A, which may vary between approximately200 nm to approximately 400 nm in some embodiments) parallel to thefirst direction, and a set of second segments 282 b extending from asecond edge of the straight portion 281 by the distance (D) parallel tothe first direction, where the second edge is opposite from the firstedge of the straight portion 281. Individual first and second segments282 a/b are located above corresponding first and second active channels220 a/b. A sum of the width Lw and the distance D may determineelectrical channel lengths (denoted as Lg) of the first and secondactive channels 220 a/b. As shown in the layout 201, individual firstsegments 282 a extend away from the edge 218 a of the outer region 217 aof the active area 215 a (or extend toward the edge 218 b of the outerregion 217 b of the active area 215 b). Similarly, individual secondsegments 282 b extend away from the edge 218 b of the outer region 217 bof the active area 215 b (or extend toward the edge 218 a of the outerregion 217 a of the active area 215 a). As such, the common gate 280 maybe regarded as a contiguous gate feature with “zig-zag” patterns or“zipper” patterns. In some embodiments, the width Lw of the straightportion 281 corresponds to a minimum feature size of the memory device.The width Lw at the minimum feature size (or greater) would providereliable bridging between individual first and second segments 282 a/b.

The layout 201 illustrates gates 225 (also identified individually as225 a/b) over the active areas 215. The gates 225 includes aspects ofthe gates 125 described with reference to FIG. 1A. For example, the gate225 a is located between the one or more source contacts located in themedial region (not shown) of the active area 215 a and the bit linecontacts 140 (e.g., the bit line contacts 140 a-c) located in the outerregion 217 a. Further, the gates 225 include sets of protruded segments227 (also identified individually as 227 a/b) extending in the firstdirection past respective edges 218 of the outer regions 217. Individualprotruded segments 227 a/b are located between two neighboring bit linecontacts 140 of the respective outer regions—e.g., bit line contacts 140a and 140 b are separated by one of the protruded segments 227 a, bitline contacts 140 d and 140 e are separated by one of the protrudedsegments 227 b. In this manner, the protruded segments 227 a/b canassist electrically isolating individual bit line contacts 140 from theneighboring bit line contacts 140 within respective outer regions 217 ofthe active area 215.

The layout 202 illustrates a first implant layer 285 laid over thelayout 201. The shaded regions of the first implant layer 285 correspondto a photoresist material configured to block one or more dopant speciesof the first implant process steps. In some embodiments, the dopantspecies for the first implant steps may include boron, indium, or othersuitable p-type dopants—e.g., dopants exhibiting positive polarity whenionized. In other embodiments, the dopant species for the first implantsteps may include phosphorus, arsenic or other suitable n-typedopants—e.g., dopants exhibiting negative polarity when ionized.Further, the first implant steps may be carried out with implantenergies large enough to penetrate the gates (e.g., the first gates 225,the common gate 280), if performed after forming the gates, but not thephotoresist material. As such, the regions of the layout 202 uncoveredby the well implant layer 285 would receive the dopant species duringthe first implant process steps. Such uncovered regions includes thefield regions (white spaces of the layout 202 corresponding to the STIisolation regions), the regions around and including the end portions221 a/b (also including portions of the segments 282 a/b of the commongate 280 and portions of the interdigitated active channels under thesegment 282 a/b proximate to the end portions 221 a/b, one of suchregions identified with box 286), and the gates 225 including theprotruded segments 227 and portions of the active areas 215 uncovered bythe resist material (e.g., under the protruded segments 227 of the gates225, one of such portions of the active area 215 identified with box287).

The dopant species for the first implant steps may be determined toincrease threshold voltages of the active area including the dopantspecies. For example, the first implants into the portions of theinterdigitated active channels proximate to the end portions 221 a/b(and under the segments 282 a/b of the common gate 280) increases thethreshold voltage for the common gate 280 (e.g., increase the localthreshold voltage of the portions implanted), which in turn helps toavoid short channel effects for the common gate 280. Similarly, thefirst implants into the portions of the active areas 215 under theprotruded segments 227 of the gates 225 (e.g., the active areaidentified with the box 287) increase the threshold voltage for theprotruded segments 227 of the gates 225, which in turn helps toelectrically isolate the bit line contacts (e.g., bit line contact 140b) from neighboring bit line contacts (e.g., bit line contacts 140 aand/or 140 c). In some embodiments, the first implant steps are carriedout with p-type dopant species (e.g., boron, indium).

Further, the layout 202 illustrates a second implant layer 290. Regions290 a and 290 b correspond to areas without a photoresist materialduring the second implant process steps while most of the region 290 cis covered by the photoresist material except openings around andincluding the end portions 221 a/b—e.g., one of such openingscorresponding to the box 286. Dopant species of the second implant stepsincludes species having an opposite polarity to the dopant species usedfor the first implant steps. The second implant steps may reduce contactresistances between the active regions open to the second implant stepsand the contacts formed therein. For example, the dopant species for thesecond implant steps may include arsenic and/or phosphorus atoms (e.g.,n-type dopants) if the first implant steps were carried out with boronand/or indium atoms (e.g., p-type dopants).

The layout 201 may be regarded as an aggressively compact layout with arelatively high risk of leakage current when compared to the layouts 203and/or 205 illustrated in FIGS. 2B and 2C. For example, an area occupiedby the layout 201 may be less than the areas occupied by the layouts 203and/or 205. However, the risk associated with leakage current issuesduring HV operations may be greater for the layout 201 when compared tothe layouts 203 and 205. In this regard, the layout 201 illustrates twocritical distances (denoted as C1 and C1 a) for the leakage current. Insome embodiments, C1 a may vary between approximately 100 nm toapproximately 400 nm, and C1 may vary between approximately 200 nm toapproximately 500 nm.

During the HV operations, the bit line contacts (e.g., the bit linecontact 140 e) are coupled to the high voltage (e.g., the erase voltagefor the memory array) while the contacts (e.g., the contact 145 a) inthe end portions 221 a of the opposing active channels 220 a are held ata low voltage (e.g., grounded). As such, the shorter the criticaldistance C1 is, the higher the risks associated with the leakage currentbetween the high voltage node (e.g., the bit line contacts 140 or theactive areas including the bit line contacts 140) and the low voltagenodes (e.g., the contacts 145 or the end portions 221 of the opposingactive channels).

Further, as the low voltage nodes are the distance C1 a away from theLDD regions of the opposing active channels connected to the highvoltage node, the leakage current may arise therebetween. In addition,the distance C1 a may be less than the critical distance C1. As the highvoltage of the bit line contacts 140 drops across the LDD regions,however, the leakage current between the LDD regions and the endportions of the opposing active channels may be less severe (althoughnon-zero, in some cases) than the leakage current between the bit linecontacts 140 and the nearest contacts 145.

FIG. 2B illustrates layouts 203 and 204 of a portion of an isolationdevice 210 in accordance with embodiments of the present technology. Thelayouts 203 and 204 include various aspects of the layouts 201 and 202described with reference to FIG. 2A. As such, descriptions directed tocommon aspects between the layouts 201/202 and 203/204 are omitted forthe layouts 203/204 to avoid duplicating the same descriptions. Severalaspects of the layouts 203 and 204 different than the layouts 201 and202 include an overall shape of the common gate 280, a distance betweenthe edges 218 a/b of the active areas 225 a/b, the critical distancebetween the high voltage nodes and the low voltage nodes (denoted as C2in the layout 203), an overall shape of the first implant layer 285,among others. For example, the distance between the edges 218 a and 218b of the layout 203 is greater than that of the layout 201. Accordingly,the critical distance C2 of the layout 203 is greater than the criticaldistance C1 of the layout 201. In some embodiments, C2 may vary betweenapproximately 400 nm to approximately 600 nm, and C2 a may vary betweenapproximately 100 nm to approximately 400 nm.

The common gate 280 of the layout 203 includes a straight portion 281having a width (denoted as Lw in FIG. 2B, which may vary betweenapproximately 200 nm to approximately 400 nm in some embodiments), a setof first segments 282 a extended from a first edge of the straightportion 281 by a distance (denoted as D in FIG. 2B, which may varybetween approximately 50 nm to approximately 250 nm in some embodiments)parallel to the first direction, and a set of second segments 282 bextending from a second edge of the straight portion 281 by the distance(D) parallel to the first direction, where the second edge is oppositefrom the first edge of the straight portion 281. The width Lw of thelayout 203 may be greater than that of the layout 203. For example, thewidth Lw of the layout 203 may be greater than the minimum feature sizeof the memory device. Further, the distance D of the layout 203 may beless than that of the layout 201. A sum of the width Lw and the distanceD of the layout 203 may be maintained the same as that of the layout201.

The layout 203 may be regarded as a mildly compact layout with a mediumrisk of leakage current when compared to the layouts 201 and/or 205illustrated in FIGS. 2A and 2C. For example, an area occupied by thelayout 203 may be greater than the area occupied by the layout 201, butless than the area occupied by the layout 205. Further, the riskassociated with the leakage current during the HV operations may begreater for the layout 203 when compared to the layout 205, but lesswhen compared to the layout 201. For example, the critical distance C2is greater than the critical distance C1 such that the leakage currentbetween the high voltage node (e.g., the bit line contacts 140 or theactive areas including the bit line contacts 140) and the low voltagenodes (e.g., the contacts 145 or the end portions 221 of the opposingactive channels) is expected to be reduced for the layout 203 whencompared to the layout 201. Moreover, although the distance C2 a may beapproximately equal to the distance C1 a, the leakage current betweenthe LDD regions and the low voltage node may be reduced for the layout203 when compared to the layout 201 because the high voltage of the bitline contacts 140 drops more across the LDD regions due to the greaterdistance between the low voltage nodes and the high voltage nodes.

FIG. 2C illustrates layouts 205 and 206 of a portion of an isolationdevice 210 in accordance with embodiments of the present technology. Thelayouts 205 and 206 include various aspects of the layouts 201 and 202described with reference to FIG. 2A. As such, descriptions directed tocommon aspects between the layouts 201/202 and 205/206 are omitted forthe layouts 205/206 to avoid duplicating the same descriptions. Severalaspects of the layouts 205 and 206 different than the layouts 201 and202 include an overall shape of the common gate 280, a distance betweenthe edges 218 a/b of the active areas 225 a/b, the critical distance(denoted as C3 in the layout 205 of FIG. 2C, which may vary betweenapproximately 450 nm to approximately 850 nm in some embodiments), anoverall shape of the first implant layer 285, among others. For example,the distance between the edges 218 a and 218 b of the layout 205 isgreater than that of the layout 201 or the layout 203. Accordingly, thecritical distance C3 of the layout 205 is greater than the criticaldistance C1 of the layout 201 or the critical distance C2 of the layout203.

The common gate 280 of the layout 205 includes a straight portion 281having a width (denoted as Lw in FIG. 2C, which may vary betweenapproximately 60 nm to approximately 400 nm in some embodiments), a setof first segments 282 a extended from a first edge of the straightportion 281 by a distance (denoted as D in FIG. 2C, which may varybetween approximately 60 nm to approximately 400 nm in some embodiments)parallel to the first direction, and a set of second segments 282 bextending from a second edge of the straight portion 281 by the distance(D) parallel to the first direction, where the second edge is oppositefrom the first edge of the straight portion 281. Individual firstsegments 282 a extend toward the edge 218 a of the outer region 217 a ofthe active area 215 a, and individual second segments 282 b extendtoward the edge 218 b of the outer region 217 b of the active area 215b. As such, the common gate 280 of the layout 205 may be regarded as acontiguous gate feature with “zig-zag” patterns similar to the commongates of the layouts 201 and 203, but with an opposite direction of the“zig-zag” patterns. In some embodiments, the width Lw of the layout 205may be greater than that of the layout 201. In other embodiments, thewidth Lw of the layout 205 may correspond to the minimum feature size ofthe memory device. A sum of the width Lw and the distance D of thelayout 205 may be maintained the same as that of the layout 201.

The layout 205 may be regarded as a conservatively compact layout with arelatively low risk of leakage current when compared to the layouts 201and/or 203 illustrated in FIGS. 2A and 2B. For example, an area occupiedby the layout 205 may be greater than the area occupied by the layout201 or the layout 203. However, the risk associated with the leakagecurrent during the HV operations may be less for the layout 205 whencompared to the layout 201 or the layout 203. For example, the criticaldistance C3 is greater than the critical distance C2 (or C1) such thatthe leakage current between the high voltage node (e.g., the bit linecontacts 140 or the active areas including the bit line contacts 140)and the low voltage nodes (e.g., the contacts 145 or the end portions221 of the opposing active channels) is expected to be reduced for thelayout 205 when compared to the layout 203 (or the layout 201).

Further, the layout 205 depicts that the contacts that are groundedduring the HV operations (e.g., the contacts 145) are located betweentwo neighboring segments 282 of the common gate 280. In view of thestraight portion 281 of the common gate 280 proximate to the endportions 221, the low voltage nodes (e.g., the grounded contacts 145,the end portions 221 including the grounded contacts 145) are surroundedon three sides such that the low voltage nodes can be better isolatedfrom the LDD regions of the neighboring active channels when compared tothe layouts 201 and/or 203. As such, the layout 205 may be least likelyto have the leakage current issues among the layouts 201, 203, and 205.

The memory devices described in detail above with reference to FIGS. 1Athrough 2C or packages incorporating such a memory device can beincorporated into any of a myriad of larger and/or more complex systems,a representative example of which is a system 380 shown schematically inFIG. 3. The system 380 can include a processor 382, a memory 384 (e.g.,SRAM, DRAM, flash, 3D NAND, 3D cross-point and/or other memory devices),input/output devices 386, and/or other subsystems or components 388. Forexample, the memory 384 may include the isolation devices described withreference to FIG. 1A through 2C (e.g., the isolation device 110, theisolation device 210 with various modifications). As such, the memorydevices of the memory 384 can include high voltage isolation deviceswith interdigitated active channels sharing a common gate. In someembodiments, the common gate is a contiguous feature include a “zig-zag”pattern. The memory devices and/or packages incorporating such memorydevices can be included in any of the elements shown in FIG. 3.

The resulting system 380 can be configured to perform any of a widevariety of suitable computing, processing, storage, sensing, imaging,and/or other functions. Accordingly, representative examples of thesystem 380 include, without limitation, computers and/or other dataprocessors, such as desktop computers, laptop computers, Internetappliances, hand-held devices (e.g., palm-top computers, wearablecomputers, cellular or mobile phones, personal digital assistants, musicplayers, etc.), tablets, multi-processor systems, processor-based orprogrammable consumer electronics, network computers, and minicomputers.Additional representative examples of the system 380 include lights,cameras, vehicles, etc. With regard to these and other example, thesystem 380 can be housed in a single unit or distributed over multipleinterconnected units, for example, through a communication network. Thecomponents of the system 380 can accordingly include local and/or remotememory storage devices and any of a wide variety of suitablecomputer-readable media.

It should be noted that embodiments illustrated above describe possibleimplementations, and that the various schemes of integrating processsteps and their sequence for the embodiments may be rearranged orotherwise modified and that other implementations are possible.Furthermore, embodiments from two or more of the modifications may becombined. From the foregoing, it will be appreciated that specificembodiments of the technology have been described herein for purposes ofillustration, but that various modifications may be made withoutdeviating from the disclosure. In addition, while in the illustratedembodiments certain features or components have been shown as havingcertain arrangements or configurations, other arrangements andconfigurations are possible. Moreover, certain aspects of the presenttechnology described in the context of particular embodiments may alsobe combined or eliminated in other embodiments.

Although in foregoing example embodiments, isolation devices ofsemiconductor devices including 3D NAND flash memory have been describedand illustrated, in other embodiments, semiconductor devices may beprovided with different types of memory arrays—e.g., 3D cross-pointmemory, DRAM, resistive memory, magnetic memory, ferroelectric memory,etc. Moreover, the present technology of modifying shapes (design,layout) of various components (e.g., gates, active areas, implantlayers) of the isolation device (or other integrated circuitry) may beapplied to semiconductor devices other than memory devices to reduceareas occupied by the isolation devices while mitigating risksassociated with leakage currents stemming from compact and denselayouts.

The devices discussed herein, including a semiconductor device, may beformed on a semiconductor substrate or die, such as silicon, germanium,silicon-germanium alloy, gallium arsenide, gallium nitride, etc. In somecases, the substrate is a semiconductor wafer. In other cases, thesubstrate may be a silicon-on-insulator (SOI) substrate, such assilicon-on-glass (SOG) or silicon-on-sapphire (SOS), or epitaxial layersof semiconductor materials on another substrate. The conductivity of thesubstrate, or sub-regions of the substrate, may be controlled throughdoping using various chemical species including, but not limited to,phosphorous, boron, indium, or arsenic. Doping may be performed duringthe initial formation or growth of the substrate, by ion-implantation,or by any other doping means.

As used herein, including in the claims, “or” as used in a list of items(for example, a list of items prefaced by a phrase such as “at least oneof” or “one or more of”) indicates an inclusive list such that, forexample, a list of at least one of A, B, or C means A or B or C or AB orAC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase“based on” shall not be construed as a reference to a closed set ofconditions. For example, an exemplary step that is described as “basedon condition A” may be based on both a condition A and a condition Bwithout departing from the scope of the present disclosure. In otherwords, as used herein, the phrase “based on” shall be construed in thesame manner as the phrase “based at least in part on.”

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thescope of the invention. Rather, in the foregoing description, numerousspecific details are discussed to provide a thorough and enablingdescription for embodiments of the present technology. One skilled inthe relevant art, however, will recognize that the disclosure can bepracticed without one or more of the specific details. In otherinstances, well-known structures or operations often associated withmemory systems and devices are not shown, or are not described indetail, to avoid obscuring other aspects of the technology. In general,it should be understood that various other devices, systems, and methodsin addition to those specific embodiments disclosed herein may be withinthe scope of the present technology.

What is claimed is:
 1. A semiconductor device, comprising: an activearea including a medial region having one or more source contacts and anouter region having a single column of bit line contacts; a plurality ofinterdigitated active channels including 1) a plurality of first activechannels connected to an edge of the outer region, wherein each one ofthe first active channels is aligned with a corresponding bit linecontact and extends in a first direction orthogonal to the single columnof bit line contacts, and 2) a plurality of second active channelsspaced away from the edge of the outer region, wherein the second activechannels are parallel to the first active channels such that individualfirst active channels alternate with individual second active channels;and a common gate over the plurality of interdigitated active channels,the common gate extending in a second direction parallel to the singlecolumn of bit line contacts and configured to couple with the pluralityof interdigitated active channels.
 2. The semiconductor device of claim1, wherein the plurality of second active channels is offset by adistance in the second direction with respect to the plurality of firstactive channels, the distance corresponding to one-half of a pitch ofthe first active channels.
 3. The semiconductor device of claim 1,wherein the first and second active channels have a width orthogonal tothe first direction, the width corresponding to a minimum feature sizeof the semiconductor device.
 4. The semiconductor device of claim 1,further comprising: a gate dielectric material between the common gateand the plurality of interdigitated active channels, a thickness of thegate dielectric material supporting relatively low voltage operations ofthe semiconductor device.
 5. The semiconductor device of claim 1,further comprising: a plurality of first contacts that each is locatedin first end portions of the first active channels, the first endportions opposite to the corresponding bit line contacts; and aplurality of second contacts that each is located in second end portionsof the second active channels, the second end portions proximate to theedge of the outer region.
 6. The semiconductor device of claim 5,wherein: individual first contacts are connected to corresponding firstpage buffers of the semiconductor device; and individual second contactsare connected to corresponding second page buffers of the semiconductordevice.
 7. The semiconductor device of claim 5, wherein the common gateis located between the plurality of first contacts and the plurality ofsecond contacts.
 8. The semiconductor device of claim 5, wherein thecommon gate comprises: a straight portion having a width orthogonal tothe second direction; a plurality of first segments extending from afirst edge of the straight portion by a distance parallel to the firstdirection, wherein individual first segments are located abovecorresponding first active channels; and a plurality of second segmentsextending from a second edge of the straight portion by the distanceparallel to the first direction, the second edge opposite from the firstedge, wherein individual second segments are located above correspondingsecond active channels.
 9. The semiconductor device of claim 8, whereinthe distance and the width, in combination, determine electrical channellengths of the first and second active channels.
 10. The semiconductordevice of claim 8, wherein: individual first segments extend away fromthe edge of the outer region of the active area; and individual secondsegments extend toward the edge of the outer region of the active area.11. The semiconductor device of claim 8, wherein: individual firstsegments extend toward the edge of the outer region of the active area;and individual second segments extend away from the edge of the outerregion of the active area.
 12. The semiconductor device of claim 8,wherein: one or more first contacts are located between two neighboringsecond segments of the common gate; and one or more second contacts arelocated between two neighboring first segments of the common gate. 13.The semiconductor device of claim 8, wherein portions of theinterdigitated active channels under the common gate include dopantatoms that increase a threshold voltage of the portions of theinterdigitated active channels.
 14. The semiconductor device of claim 1,further comprising: a gate over the active area and located between theone or more source contacts and the single column of bit line contacts,the gate extending in the second direction.
 15. The semiconductor deviceof claim 14, wherein the gate comprises a plurality of protrudedsegments extending in the first direction past the edge of the outerregion, individual protruded segments located between two neighboringbit line contacts.
 16. The semiconductor device of claim 15, whereinportions of the outer region of the active area under the protrudedsegments of the gate includes dopant atoms that increase a thresholdvoltage of the portions of the outer region.
 17. A semiconductor device,comprising: an active area including a medial region having a column ofsource contacts and an outer region having a column of bit linecontacts; a first gate over the active area, the first gate including 1)a straight portion located between the columns of source contacts andbit line contacts and 2) a plurality of protruded segments connected tothe straight portion, wherein individual protruded segments extend pastan edge of the outer region in a first direction orthogonal to thecolumn of bit line contacts and are located between two neighboring bitline contacts; a plurality of first active channels connected to theedge of the outer region, wherein each one of the first active channelsis aligned with a corresponding bit line contact and extends in thefirst direction; and a second gate over the plurality of first activechannels, the second gate extending in a second direction parallel tothe column of bit line contacts.
 18. The semiconductor device of claim17, further comprising: a plurality of second active channels spacedaway from the edge of the outer region, each one of the second activechannels extending in the first direction, wherein: the plurality offirst active channels and the plurality of second active channels form aplurality of interdigitated active channels such that individual firstactive channels alternate with individual second active channels; andthe second gate is over the plurality of interdigitated active channelsand configured to couple with the plurality of interdigitated activechannels.
 19. A semiconductor device, comprising: a first active areaincluding a first medial region and a first outer region with a singlecolumn of first bit line contacts; a plurality of first active channelsconnected to an edge of the first outer region, wherein each one of thefirst active channels is aligned with a corresponding first bit linecontact and extends in a first direction orthogonal to the single columnof first bit line contacts; a second active area including a secondmedial region and a second outer region with a single column of secondbit line contacts; a plurality of second active channels connected to anedge of the second outer region, wherein each one of the second activechannels is aligned with a corresponding second bit line contact andextends in the first direction, and wherein: the first outer regionfaces the second outer region; and the plurality of first activechannels and the plurality of second active channels form a plurality ofinterdigitated active channels such that individual first activechannels alternate with individual second active channels; and a commongate over the plurality of interdigitated active channels, the commongate extending in a second direction parallel to the single column offirst bit line contacts and configured to couple with the plurality ofinterdigitated active channels.
 20. The semiconductor device of claim19, wherein the first and second active channels have a width orthogonalto the first direction, the width corresponding to a minimum featuresize of the semiconductor device.